The present invention generally relates to surgery on body tissues and organs. More specifically, the present invention relates to a method and apparatus for temporarily immobilizing a local area of tissue subject to motion, such as the heart wall, which permits a treatment procedure to be performed on that local area of tissue.
Coronary artery disease remains the leading cause of morbidity and mortality in Western societies and is manifested in a number of ways. For example, disease of the coronary arteries can lead to insufficient blood flow to various areas of the heart. This can lead to the discomfort of angina and the risk of ischemia. In severe cases, acute blockage of coronary blood flow can result in irreversible damage to the myocardial tissue, including myocardial infarction and the risk of death.
A number of approaches have been developed for treating coronary artery disease. In less severe cases, it is often sufficient to merely treat the symptoms, with pharmaceuticals, or treat the underlying causes of the disease, with lifestyle modification. In more severe cases, the coronary blockage can be treated endovascularly or percutaneously using techniques such as balloon angioplasty, atherectomy, laser ablation, stents, and the like.
In cases where these approaches have failed or are likely to fail, it is often necessary to perform a coronary artery bypass graft procedure. This procedure generally involves opening the chest by median sternotomy, spreading the left and right rib cage apart; and opening the pericardial sac to achieve direct access to the heart. Next, a blood vessel or vessels for use in the graft procedure are mobilized from the patient. This usually entails mobilizing either a mammary artery or a saphenous vein, although other graft vessels may also be used.
Commonly, a heart-lung or cardiopulmonary bypass is performed so that the beating of the heart can be stopped during the surgical procedure. This usually entails arterial and venous cannulation, connecting the bloodstream to a heart-lung machine, cooling the body to about 32 degrees Celsius, cross-clamping of the aorta and cardioplegic perfusion of the coronary arteries to arrest and cool the heart to about 4 degrees Celsius. The arrest or stoppage of the heart is generally required because the constant pumping motion of the beating heart would make surgery upon the heart difficult in some locations and extremely difficult if not impossible in other locations
Once cardiac arrest is achieved, a graft (or grafts) is attached to the relevant portions of a coronary artery (or arteries) followed by weaning from the cardiopulmonary bypass, restarting the heart, and decannulation. Finally the chest is closed.
However, use of the cardiopulmonary bypass may create difficulties for the patient and increase the expense and time required for the procedure. In a cardiopulmonary bypass, all the patient""s blood, which normally returns to the right atrium, is diverted to a system which supplies oxygen to the blood, removes carbon dioxide, and returns the blood, at sufficient pressure, into the patient""s aorta for further distribution into the body. Generally, such a system requires several separate components, including an oxygenator, several pumps, a reservoir, a blood temperature control system, filters, and flow, pressure, and temperature sensors.
Problems may develop during cardiopulmonary bypass due to biological reaction of the blood to non-endothelially lined surfaces, i.e. surfaces unlike those of a blood vessel. In particular, exposure of blood to foreign surfaces results in the activation of virtually all the humoral and cellular components of the inflammatory response, as well as some of the slower reacting specific immune responses. Other complications from cardiopulmonary bypass include loss of red blood cells and platelets due to shear stress damage. In addition, cardiopulmonary bypass requires the use of an anticoagulant, such as heparin. The anticoagulant may, in turn, increase the risk of hemorrhage. Finally, cardiopulmonary bypass sometimes necessitates administering additional blood to the patient. The additional blood, if from a source other than the patient, may expose the patient to blood borne diseases.
Due to the risks incurred during cardiopulmonary bypass, others have attempted to perform a coronary artery bypass graft procedure without cardiac arrest and cardiopulmonary bypass in a procedure known as an xe2x80x9coff pump coronary artery bypassxe2x80x9d (OPCAB) procedure. For example, Trapp and Bisarya (Annals Thorac. Surg. 19(1):1-9, 1975), immobilized the area of the bypass graft by encircling sutures deep enough to incorporate enough muscle to suspend an area of the heart while preventing damage to the coronary artery. More recently, Fanning et al (Annals Thorac. Surg. 55: 486-489, 1993) reported immobilizing the area of the bypass graft with stabilization sutures.
While these attempts have achieved some success, they generally require enhanced skill of the surgeon to properly create the anastomosis because, even with use of sutures to suspend a portion of the surface of the heart upon which the surgery is conducted, the beating heart continues to move in the relevant area more than desired. In addition, the sutures may cause a myocardial tear, an injury of the coronary artery branches, or such complications as embolism or focal arteriosclerosis resulting from the pressures of the ligatures upon the artery.
In order to solve such problems associated with the use of sutures to stabilize the site of an anastomosis upon the surface of a beating heart, a device known as a xe2x80x9clocal myocardial compression devicexe2x80x9d has been developed wherein myocardial portions on both sides of the coronary artery on which anastomosis is to be performed are compressed with two-tined fork-like instrument to apply pressure upon the artery and the heart itself so as to stabilize the treatment site. While use of this device has met with some success, the application of local compression to the heart can effect considerable local deterioration of cardiac function, particularly when cardiopulmonary bypass is not used to supplement blood circulation. In addition, this device does not address the problem of bleeding from a locally dissected coronary artery intended for anastomosis.
To address the undesirable effect of compression of the heart, such as is caused by use of the local myocardial compression device, a suction-assisted device has been developed having two paddles, each of which includes a series of suction ports located at the point where the device interfaces with the surface of the heart as described in U.S. Pat. No. 5,836,311. The paddles are applied to the surface of the heart across an arterial section intended as an anastomotic site and suction applied through the suction ports is employed to lift and hold the surface tissue of a beating heart at the anastomotic site to minimize motion of the treatment site while the heart continues to beat underneath. This device may be used in either a conventional, open-chest environment or in an endoscopic minimally invasive procedure. However, it has been discovered that application of pressure at localized points using such a device can cause suction induced hemorrhages on the surface of the heart that result in scarring of the heart.
The need for stabilization of a moveable surgical or biopsy site (i.e., a treatment site) is not limited to the case of the beating heart. Endoscopic catheters, for example biopsy and angiogenesis catheters, are known for use in connection with procedures involving removal of small tissue samples or injection of therapeutic drugs or genetically altered structures, such as for use in gene therapy. For accuracy of results, it is important that the depth of the tissue sample or injection be precisely controlled. When such endoscopic catheters are used at interior areas of the body that are subject to movement, such as the bowel or stomach, the lungs and the diaphragm, it is especially difficult to assure that the injection or tissue sampling device penetrates the target tissue to a desired or uniform depth. Such procedures could be facilitated by use of a device adapted for use at the tip of an endoscopic catheter that helps to stabilize the treatment site during such a therapeutic or diagnostic procedure.
Thus, there is a need in the art for new and better devices useful for stabilizing a surgical site, such as the surface of the beating heart, or for endoscopically stabilizing a an interior therapeutic or diagnostic treatment site.
In spite of the fact that off-pump coronary artery bypass surgery undertaken on the patient""s beating heart (OPCAB) usually is successful with quick recovery of the patient and speedy return to work, many cardiovascular surgeons hesitate to perform such surgery because it requires an extremely highly-advanced skill and a special talent for avoiding the accompanying risks of complications to the coronary artery. It is an object of the present invention to provide a device to securely hold a surgical site, such as an anastomotic site on a coronary artery, relatively motionless throughout a bypass operation so that even surgeons having ordinary cardiovascular surgical skills can undertake such surgery with considerably reduced risk of complications.
It is a further object of the present invention to provide a device for holding an anastomotic site of a coronary artery motionless for an off-pump bypass operation without inviting deterioration of cardiac function during the operation caused by application of compression to the heart and without inviting scarring of the surface of the heart caused by application of the device.
It is a further object of the present invention to provide a practical device to hold an anastomotic site of the coronary artery motionless and bloodless during a bypass operation by restraining the bleeding from a dissected portion of the coronary artery for anastomosis.
Thus, it is an object of the present invention to provide a method and apparatus for temporarily immobilizing a local surgical site, such as an area of a beating heart, without requiring the use of stabilizing sutures.
It is a further object of the present invention to provide a disposable suction body for use in anastomosis of an autograph to the surface of a treatment site wherein the suction body includes a release mechanism so that the suction body can remain in place at an anastomotic site while the anastomosis is completed, and then the release mechanism can be actuated to remove the suction body from around the graft protruding from the anastomosis.
It is a further object of the present invention to provide a suction device for attachment to the tip of an endoscopic catheter for stabilizing a treatment site located at the interior of the body to facilitate injection of a drug or obtaining a tissue sample from a moving bodily part.
These and other objectives are met by the present invention, which provides a suction body and method of its use for temporarily immobilizing a local area of tissue. The invention flexible suction body comprises a suction channel containing a ring-shaped base defining an opening for exposing a treatment site, an outer flared, spreadable rim attached along the outer periphery of the base, a inner rim attached along the inner periphery of the base, a suction port for applying a partial vacuum within the suction channel, and at least one drain aperture in the suction body adapted for removing fluid from the treatment site while a partial vacuum is maintained in the suction channel. The suction device is coupled to a source of negative pressure.
In a preferred embodiment, the tip of the flared outer rim of the invention suction channel is sufficiently flexible that application of a partial vacuum to the suction body while the outer rim is in contact with the treatment site causes the outer rim to flatten and spread outwardly across the surface of the treatment site. By this means a soft edge for the suction channel is created to avoid bruising of the underlying tissue. As the spreading of the outer rim also enlarges the suction field to apply the partial vacuum over an increased tissue area, localized hemorrhage (e.g., of capillaries) caused by the suction is minimized or avoided.
The present invention further provides methods for stabilizing a treatment or treatment site utilizing the invention suction bodies. The invention method comprises placing an invention suction body upon the surface of the treatment site wherein the suction body is placed with the tip of the outer rim against the treatment site, and applying sufficient partial vacuum to the suction channel via the suction port to cause the suction body to attach to the treatment site while the outer rim flattens and extends outwardly thereby stabilizing the treatment site. In one embodiment, the suction body further comprises a detachable handle attached to the exterior of the suction body wherein the handle is formable, but can be locked into a fixed orientation with respect to the suction body. In another embodiment, the invention suction body is sized for attachment to the tip of an endoscopic catheter, such as an injection catheter or a biopsy catheter.